Multi-Pin Dense Array Resistivity Probe

ABSTRACT

Resistivity probes can be used to test integrated circuits. In one example, a resistivity probe has a substrate with multiple vias and multiple metal pins. Each of the metal pins is disposed in one of the vias. The metal pins extend out of the substrate. Interconnects provide an electrical connection to the metal pins. In another example, a resistivity probe has a substrate with a top surface and multiple elements extending from the substrate. Each of the elements curves from the substrate to a tip of the element such that each of the elements is non-parallel to the top surface of the substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to the provisional patent applicationfiled Aug. 22, 2016 and assigned U.S. App. No. 62/378,161, thedisclosure of which is hereby incorporated by reference.

FIELD OF THE DISCLOSURE

This disclosure relates to resistivity probes.

BACKGROUND OF THE DISCLOSURE

Evolution of the semiconductor manufacturing industry is placing evergreater demands on yield management and, in particular, on metrology andinspection systems. Critical dimensions are shrinking while wafer sizeis increasing. Economics is driving the industry to decrease the timefor achieving high-yield, high-value production. Thus, minimizing thetotal time from detecting a yield problem to fixing it determines thereturn-on-investment for the semiconductor manufacturer.

It is necessary to test integrated circuits as part of the manufacturingprocess. The testing is performed by creating a temporary electricalcontact between a test probe or probes with selected points on theintegrated circuit or witness sample being tested. A predeterminedprogrammed test is then undertaken utilizing signals applied to thecircuit and derived therefrom through the probes. Because of thecomplexity and the small size of the circuits, particularly extremelycompact integrated circuits, the numbers of contacts that must be madewith the circuit for appropriate testing demands strict control over thepositioning of contact probes. Furthermore, the force with which theprobes are placed against the predetermined circuit pads or points maybe important. Controlling the precise positioning of the probes as wellas the force on each probe requires accuracy in the manufacture of probesystems.

Such probe systems have typically used probes that are normally in theform of fine needles. The probes are individually attached to a printedcircuit board by either soldering the probe directly to the printedcircuit board or to a holding device which in turn is soldered to theprinted circuit board. The probes typically extend from the mountingplace, such as the blade, in a cantilever arm fashion reaching out asmuch as several hundred mils to the point on the integrated circuit tobe tested. To change the force on the probe requires either changing theprobe diameter to make the probe stiffer or more flexible, or changingthe probe length or cantilever length. Furthermore, the use of suchprobes does not provide a convenient means for implementing a controlledimpedance transmission line.

In an instance, a four-point probe can be used to test the electricproperties of an integrated circuit by generation of resistivity orcarrier concentration profiles of the surface of a processedsemiconductor wafer. A conventional four-point probe technique typicallyhas the points positioned in an in-line configuration. By applying acurrent to the two peripheral points, a voltage can be measured betweenthe two inner points of the four-point probe. Thus the electricresistivity ρ of the test sample can be determined through the equationρ=c(V/I), wherein V is voltage measured between inner points, wherein Iis current applied to the peripheral points and, wherein c is a geometryfactor depending on the surface contact separation d and the dimensionsof the test sample.

Conventionally probe tips are made by planar microelectromechanicalsystems (MEMS) manufacturing processes. The probe cantilevers extend outparallel to the supporting body surface, which is referred to asplanarity, for easy manufacturing as well as simultaneous landing on aflat wafer surface. When the cantilever makes contact with wafersurface, it bends and scrubs with wafer surface and form a sizeablecontact. The contact size is relevant to the contact force and probewear. This design eventually loses conductive materials, loses thecapability for passing electric current thereby limiting precision ofthe measurement, and shortens the lifetime of the probe. Due to theco-planarity of probe tip to the supporting chip surface, and the angleabout 30° between the cantilevered probes to wafer surface, the contactsize is variable related to probe tip wear, and the conductive coatingcan be easily removed during landing and measurement. A change ofcontact size and removal of conductive coating will deteriorate themeasurement accuracy, shortening probe lifetime significantly.

The metal coating deforms and quickly wears off on existing probes,which results in an approximate lifetime of 100-500 touches ormeasurements. The fragile SiO₂ cantilevers also can easily break.Therefore, improved resistivity probe designs are needed.

BRIEF SUMMARY OF THE DISCLOSURE

In a first embodiment, a resistivity probe is provided. The resistivityprobe comprises a substrate defining a plurality of vias, a plurality ofmetal pins in one or more rows, and a plurality of interconnects in thesubstrate. Each of the metal pins is disposed in one of the vias. Eachof the metal pins extends out of the substrate. The interconnectsprovide an electrical connection to the metal pins.

An arm can be included. The substrate can be disposed on the arm. Aplaten also can be included. The arm can be configured to move thesubstrate toward and away from the platen.

The metal pins can be fabricated of tungsten, tungsten carbide, atungsten-rhenium alloy, a beryllium-copper alloy, or an alloy containinggold, palladium, platinum, silver, copper, and zinc.

The resistivity probe can include a plurality of springs. Each of themetal pins may include one of the springs.

The pins may be in an array having at least two rows. Each of the rowsincludes at least two metal pins.

In an instance, the resistivity probe includes a plurality of needlebodies, a plurality of conductive wires, an enclosure, and a fluidsource. Each of the metal pins is disposed on one of the needle bodies.Each of the needle bodies includes a main body and a shoulder portion.Each of the conductive wires is disposed on one of the needle bodies.Each of the needle bodies is positioned to extend through a wall of theenclosure. The fluid source is configured to direct a fluid into theenclosure. The needle bodies are configured to move through theenclosure upon exposure to the fluid. One of the shoulders is configuredto halt movement of the needle body that the shoulder is disposed on.The resistivity probe can further include an arm that the enclosure isdisposed on. A platen also can be included. The arm can be configured tomove the enclosure toward and away from the platen.

In a second embodiment, a method is provided. A hole is etched in a basematerial of a substrate. A wall of the through hole defines a cap stop.The wall of the through hole is lined with a release layer. Metal isdeposited in the through hole and cap stop. The metal is planarized suchthat the metal is flush with the base material thereby forming a pin.The release layer is etched.

The method can further include lining the metal with the release layerafter the planarizing and depositing a conductor on the release layerprior to the etching. The conductor and the metal are independent ofeach other after the etching.

The method can further include depositing a conductor on the metal andthe release layer after the planarizing and prior to the etching. Themetal and the conductor are in contact after the etching. The tip of themetal at a point opposite the conductor may be etched.

Forming the pin can further comprise depositing an insulator on thethrough hole and cap stop prior to the lining. The tip of the metal at apoint opposite the conductor may be etched. The base material may begrounded and/or a ground layer can be deposited surrounding theconductor.

In a third embodiment, a resistivity probe is provided. The resistivityprobe comprises a substrate defining a top surface and a plurality ofprobes extending from the substrate. Each of the probes curves from thesubstrate to a tip of the probe such that each of the elements isnon-parallel to the top surface of the substrate.

Each of the probes can includes two layers of material. The two layershave different stresses thereby causing the curve.

The substrate can include a support region that matches a curve of theprobes. The support region of the substrate is etched away.

DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and objects of the disclosure,reference should be made to the following detailed description taken inconjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of an embodiment of a resistivity probe inaccordance with the present disclosure;

FIG. 2 is a bottom view of the resistivity probe of FIG. 1;

FIG. 3 is a cross-sectional view of the resistivity probe of FIG. 1along line A-A in FIG. 2;

FIG. 4 illustrates an embodiment of pins for the resistivity probe ofFIG. 1;

FIGS. 5A-5C illustrate pin configurations;

FIGS. 6A-6H illustrate a first embodiment of a manufacturing process ofthe resistivity probe of FIG. 1, wherein the pins can move relative tothe probe body;

FIGS. 7A-7H illustrate a second embodiment of a manufacturing process ofthe resistivity probe of FIG. 1, wherein the pins can move relative tothe probe body;

FIG. 8A-8I illustrate a third embodiment of a manufacturing process ofthe resistivity probe of FIG. 1;

FIG. 9 illustrates a substrate with a quadrant populated;

FIG. 10 illustrates a linear array;

FIG. 11 illustrates another embodiment of a manufacturing process forpart of a resistivity probe;

FIG. 12 is a top view of a chip probe wafer;

FIG. 13 is a diagram of a checkerboard chip probe;

FIG. 14 is a cross-sectional block diagram of a probe head;

FIG. 15 is block diagram of a probe head on a control arm;

FIG. 16 illustrates a bottom view of variable-shaped probe pins;

FIG. 17 illustrates a side view of the variable-shaped probe pins ofFIG. 16;

FIG. 18 illustrates a second embodiment of a resistivity probe inaccordance with the present disclosure showing cross-sectional andcorresponding top views;

FIGS. 19A-19E illustrate an embodiment of a manufacturing process forpart of the resistivity probe of FIG. 18; and

FIGS. 20A-20E illustrate another embodiment of a manufacturing processfor part of the resistivity probe of FIG. 18.

DETAILED DESCRIPTION OF THE DISCLOSURE

Although claimed subject matter will be described in terms of certainembodiments, other embodiments, including embodiments that do notprovide all of the benefits and features set forth herein, are alsowithin the scope of this disclosure. Various structural, logical,process step, and electronic changes may be made without departing fromthe scope of the disclosure. Accordingly, the scope of the disclosure isdefined only by reference to the appended claims.

Embodiments of the resistivity probes disclosed herein can be used fordetermining sheet resistance in limited spaces like test pads on asemiconductor wafer. Embodiments of the resistivity probes disclosedherein also can be used to characterize magnetic random access memory(MRAM) stacks by using four-point probe measurements at severaldifferent pin spacing via current in-plane tunneling (CIPT) or othertechniques. Other devices on an integrated circuit also may be tested.The pins disclosed herein have improved wear characteristics and canincrease the lifetime of the resistivity probe by several hundredpercent. The vertical pin motion eliminates the scrubbing action of thecantilever method, which further reduces wear and eliminates breakingfrom over-flexing. The use of air pressure can eliminate pin forcevariation caused by landing height or pin planarity variations. Verticalcompliance can be substantially increased, which can make the landingmethod less critical.

FIG. 1 is a perspective view of an embodiment of a resistivity probe100. FIG. 2 is a bottom view of the resistivity probe 100 of FIG. 1.FIG. 3 is a cross-sectional view of the resistivity probe 100 of FIG. 1along line A-A in FIG. 2. The pins 102, which may be fixed in place inan instance, are positioned in a surface of a body 101 of theresistivity probe 100. The body 101 may be silicon. The pins 102 can besolid metal. The pins 102 can be stationary within a body 101 or can bedisplaced vertically using a separate spring force. Each of the pins 102can be positioned in a via through the body 101. The via can extendentirely through the body 101 or only partly through the body 101.

Nine pins 102 are illustrated. The resistivity probe 100 may includemore or fewer pins 102 than illustrated in FIG. 1. The pins 102 may bein one or more rows. For example, twelve pins 102 may be included.Different arrangements of pins 102 from that illustrated in FIGS. 1 and2 are possible. More or fewer rows or series can be included. FIG. 5A-5Cillustrate various examples of pin configurations. As seen in FIGS.5A-5C, the distance 106 is greater than the distance 104, which isgreater than the distance 105. Thus, multi-row array (like in A) orstaggered array (like in B) can provide a smaller depth of penetrationfor a given minimum feature size than a single row of pins (like in C).

Turning back to FIGS. 1-3, each of the pins 102 may have a planar tip.The dimensions of the tips can be on the micron scale. Minimum spacingof approximately 0.1 microns may be used, though other dimensions arepossible.

Instead of being fixed, each of the pins 102 may be positioned on aspring.

Instead of being fixed, each of the pins 102 also may use air pressureas a spring. The pins 102 or the body 101 can serve as a piston. Thiscan enable programmable pin 102 pressure. For example, the air pressurecan increase until Ohmic contact is made with the pins.

When pins 102 move relative to the body 101, then the pins 102 canconform to uneven surfaces, such as warped wafers. A change in height ofthe pin 102 can cause a change in deflection that may appreciably changethe tip force but the air pressure version will maintain constantpressure between pins 102. There may be some coordination between stopheight and pin height variation.

The spacing between the pins 102 can vary depending on the application.

FIG. 4 illustrates an embodiment of pins for the resistivity probe 100of FIG. 1. The pins illustrated in FIG. 4 have rounded tips, unlike theflat tips illustrated in FIG. 1. The pins can have a sub-micro pitch andimproved durability. The pins can be configured for both magnetic tunneljunctions (MTJ) CIPT and implants. While illustrated as rounded in FIG.4, the shape of the tip of pins can vary from pointed to rounded toflat. Pointed can provide good penetration, but may have limited currentcarrying capability. Rounded can increase contact area and contactresistance as well as reducing penetration. Flat can give the largestcontact area and carry the most current, but may have low penetrationwhich is limited for surfaces that oxidize.

Turning back to FIG. 1, the pins 102 may be configured to providelimited motion in the Z direction. This may prevent or reduce the needfor scrubbing. Scrubbing can aid in penetration through a top barrierlayer (e.g., an oxide). Scrubbing also can increase foot print, increaseparticles, increase amount of tip contamination from the surface beingprobed, and increase contact resistance from loose particles. Siliconmay be especially prone to loose particles and increased contactresistance. One possible mechanism is that material piles up fromscrubbing the pin and rests on the pile or a particle thereby increasingcontact resistance. Other mechanisms may be possible.

Scrubbing may be avoided unless there are limited options to breakthrough a surface layer on the pins 102, such as with roughness.Roughness can include use of a large grain material, such as tungstencarbide, that includes micro penetration points. Any scrubbing forcleaning the tips of the pins 102 may be performed off the sample.

In an instance, the pins 102 can provide a minimum 100,000 contactlifetime. A sharper tip may wear more quickly. A flat tip surface mayminimize wear, and if the pin 102 has vertical side walls it will notchange contact area as the pin 102 wears. Lifetimes also can beextremely long for hard metals. Tungsten carbide pins 102 can beconstructed so that the pin 102 surface area will not change withseveral million contacts.

The pins 102 can provide a constant contact force independent on Zheight. The pins 102 also can provide a constant contact area over pinlife.

The electrical contact of the pins 102 may include one or more of thefollowing properties. The pins 102 can provide low Ohmic contact, whichmay be below 100 Ohm-cm². The pins 102 may have the ability to penetrateblocking layers. The pins 102 may be non-contaminating, self-cleaning,and/or non-scrubbing. Controllable contact pressure (e.g., mechanicalspring or air pressure) can be provided using the pins 102. All pins 102may be able to contact the sample surface with the same pressure.

The resistivity probe 100 can miniaturize the vertical pin design of afour-point probe methodology. For example, a size of the resistivityprobe 100 may be more than 1,000 times smaller than commercial verticalfour-point probes.

The pins 102 can be fabricated of tungsten, tungsten carbide, atungsten-rhenium alloy, a beryllium-copper alloy, or an alloy containinggold, palladium, platinum, silver, copper, and zinc. Other metals,alloys, or materials for the pins 102 are possible. See the followingtable for properties of some exemplary materials for the pins 102.

Tungsten- Beryllium- Properties Tungsten Rhenium Paliney ®7 CopperPhysical Properties Density (gm/cm³) 19.24 19.29 11.81 8.35 ElectricalProperties Resistivity at 20° C. 5.59-5.86 9.15-9.65 30.9-34.9 6.10-7.93(μΩ-cm) Conductivity at 20° C. 0.179-0.170 0.109-0.104 0.032-0.29 0.131-0.126 (1/MΩ-cm) Thermal Properties Melting Point (° C.) 3410 31081015 870-980 Coeff. of Lin. Exp. 4.45 × 10⁻⁶ 4.92 × 10⁻⁶ 13.5 × 10⁻⁶17.8 × 10⁻⁶ (0 to 500° C.) (mm/mm × 1/° C.) Material Properties ElasticModulus (Gpa) 394.5 ± 6.1 395.7 ± 6.4 121.2 ± 4.9 131.5 ± 5.5 TensileYield Strength 2.65-2.90 2.90-3.36 0.65-0.93 1.38-1.64 (Gpa) UltimateTensile 4.25-4.85 5.00-5.75 0.97-1.17 2.70-3.00 Strength (Gpa) VickertsHardness 665-738 745-877 320-357 288-384 (100 gm load) (kg/mm²)

Tungsten can be used for wafer probing on aluminum pads. Tungsten'shardness provides long probe life, and the spring characteristics aredesirable for probe stability. Contact resistance is acceptable for mostapplications. Due to tungsten's fibrous nature, oxide crystals tend tobecome trapped in the probe tip, so cleaning may be needed to keepcontact resistance at acceptable levels.

Tungsten-rhenium (e.g., 97% tungsten, 3% rhenium) has properties similarto tungsten, but it is not as fibrous and does not tend to trap oxidecrystals. Contact resistance is higher than tungsten, but it is constantwith time. Tungsten-rhenium may require less maintenance than tungsten,so its life expectancy is generally higher.

Beryllium-copper (BeCu) can be used where applications require lowcontact resistance or high current. Beryllium-copper is relatively soft.Thus, probe tips wear faster than other materials, but may beself-cleaning. Beryllium-copper probes are generally used inapplications where hardness requirements are less stringent, such asgold pads.

Paliney® 7 (sold by Deringer-Ney Inc. in Vernon Hills, Ill.) containsgold, palladium, platinum, silver, copper, and zinc, and is harder thanberyllium-copper. This alloy is expensive and may be used forapplications that require low contact resistance and good conductivity.Thus, this alloy may be used for contacting gold pads.

Tungsten carbide has an even larger grain structure. This aids in oxidepenetration for non-scrubbing tips, but increases contamination forscrubbing probes. Based on these properties, tungsten-rhenium may beused for scrubbing tips and tungsten carbide may be used fornon-scrubbing probes.

Carbon nanotubes also can be used as the pins 102. Each pin 102 can be asingle carbon nanotube. The nanotubes can be attached to a support armor can be placed into appropriate sized holes. Wires can be attached toone end of the nanotube to facilitate the electrical measurement.

As seen in FIG. 3, each pin 102 is connected to an interconnect 103 inthe body 101 of the resistivity probe 100. The pins 102, while extendingfrom the body 101 to an equal distance, can extend to different depthsinto the body 101. Thus, the interconnects 103 may be at differentdepths within the body 101 so the interconnects 103 do not cross. In aninstance, the pins 102 are tungsten and the interconnects 103 aretungsten or copper.

FIGS. 6A-6H illustrate a first embodiment of a manufacturing process ofthe resistivity probe of FIG. 1. In FIG. 6A, a substrate 200 isillustrated. A through hole 201 with two diameters is etched in thesubstrate 200 in FIG. 6B. Thus, the through hole 201 also includes a capstop. A release layer 202 (e.g., SiO₂, photoresist, aerogel) isdeposited on the through hole 201 and bottom of the base material of thesubstrate 200 in FIG. 6C. In FIG. 6D, metal 203 is deposited into thethrough hole 201. The metal 203 can be used to form a pin. In FIG. 6E,the top of the metal 203 is planarized, such as using chemicalmechanical planarization. After the planarizing, the metal 203 may beflush with the base material of the substrate 200. A release layer 202is added to the top of the substrate 200 in FIG. 6F. A conductor 204 (orconductor trace) is deposited on the release layer 202 in FIG. 6G.Depositing the conductor 204 may include a masking step (notillustrated). The conductor 204 can serve as an interconnect or spring.In FIG. 6H, the release layer 202 is etched, leaving the pin made of themetal 203 and the conductor 204 independent of one another. The tip ofthe metal 203 can be shaped as needed by etching. This technique mayavoid the need for a lateral scrub. Air can be used as a primary loadsource or can be used to enhance or replace the primary load source.

FIGS. 7A-7H illustrate a second embodiment of a manufacturing process ofthe resistivity probe of FIG. 1. In FIG. 7A, a substrate 200 isillustrated. A through hole 201 with two diameters is etched in thesubstrate 200 in FIG. 7B. Thus, the through hole 201 also includes a capstop. A release layer 202 (e.g., SiO₂) is deposited on all surfaces ofthe base material of the substrate 200 in FIG. 7C. In FIG. 7D, metal 203is deposited into the through hole 201. The metal 203 can be used toform a pin. In FIG. 7E, the top of the metal 203 is planarized, such asusing chemical mechanical planarization. After the planarizing, themetal 203 may be flush with the base material of the substrate 200. InFIG. 7F, a conductor 204 (or conductor trace) is deposited on the metal203 and release layer 202. Depositing the conductor 204 may include amasking step (not illustrated). The conductor 204 can serve as aninterconnect or spring. In FIG. 7G, the release layer 202 is etched. Thetip 205 of the metal 203 is etched in FIG. 7H. In this embodiment, theconductor 204 is disposed on the metal 203. This technique creates alateral scrub. Air can be used as a primary load source. A chip usingthis design may be hermetically sealed.

FIGS. 8A-8I illustrate a third embodiment of a manufacturing process ofthe resistivity probe of FIG. 1. In FIG. 8A, a substrate 200 isillustrated. A through hole 201 with two diameters is etched in thesubstrate 200 in FIG. 8B. Thus, the through hole 201 also includes a capstop. An insulator 206 (e.g., SiO₂) is deposited on all surfaces of thebase material of the substrate 200 in FIG. 8C. A release layer 202(e.g., SiO₂) is deposited on the insulator 206 in FIG. 8D. In FIG. 8E,metal 203 is deposited into the through hole 201. The metal 203 can beused to form a pin. In FIG. 8F, the top of the metal 203 is planarized,such as using chemical mechanical planarization. After the planarizing,the metal 203 may be flush with the base material of the substrate 200.In FIG. 8G, a conductor 204 (or conductor trace) is deposited on themetal 203 and release layer 202. Depositing the conductor 204 mayinclude a masking step (not illustrated). The conductor 204 can serve asan interconnect or spring. In FIG. 8H, the release layer 202 is etched.The tip 205 of the metal 203 is etched in FIG. 8I. A metal layer forshielding or grounding may be added with the insulator layer. Air can beused as a primary load source. A chip using this design may behermetically sealed.

In the embodiment of FIG. 8, the body of the substrate 200 may begrounded. The surrounding body may be isolated from the common body. Forexample, the conductor 204 may be connected to the body of the substrate200. A grounding layer also may surround the metal 203.

In the embodiments of FIGS. 6-8, the through hole 201 is an example of avia in FIG. 1. However, the vias in FIG. 1 do not necessarily extendthrough the entire body of the probe.

FIG. 9 illustrates a substrate with a quadrant populated. The embodimentof FIG. 9 can provide moving pins 301. In this single quarter populatedembodiment, the substrate 300 is silicon but could be another material.The pins 301 can be tungsten carbide or other materials. The conductorlines 302 can be tungsten carbide or other materials. The conductorlines 302 can act as springs. The pins 301 and any springs can include arelease layer (e.g., SiO₂) that can be etched away. The springdimensions can vary to match a spring constant. The pins 301 and springscan be deposited in one step or can be deposited in three steps if arelease layer is etched away. Etching the release layer away leaves thesprings and pins 302 as independent, which can relieve lateral stress.The conductor lines 302 may be configured to be perpendicular to thecircularly, flat surface of the substrate 300. The pins 301 may not beflexible, though the springs may be flexible.

FIG. 10 illustrates a square or linear array. The substrate 400 issilicon or can be another material. The pins 401, which can move, can betungsten carbide or other materials. The conductor lines 402 can becopper or other materials. The pins 401 and any springs can include arelease layer (e.g., SiO₂) that can be etched away. The pin 401 loadingmay be entirely by air pressure. The backside of the substrate 400 maybe coated with a sacrificial layer to create a pin extension. The wiretraces of the conductor lines 402 can bend, but may not provide springaction. This embodiment can include curved elements that are notparallel to the supporting surface for their entire length.

FIG. 11 illustrates another embodiment of a manufacturing process forpart of a resistivity probe. FIG. 11 is a top view of a substratesurface. In FIG. 11A, a metal 400 is deposited and trenches 401 areetched in the surface. The set of metal lines of the metal 400 may be,for example, 1 μm by 1 μm. In FIG. 11B, an insulator 402 is deposited tooverfill the trenches 401. Then a metal 400 is deposited on theinsulator 402 and trenches are etched in the surface in FIG. 11C. Thisforms a second set of metal lines of the metal 400, which may be, forexample, 1 μm by 1 μm. This process can be repeated to create a stack ofconductors to equal the width of the conductors. When the chips fromFIG. 12 are rotated 90 degrees, the chip should look like FIG. 13.Whereas other processes create the pins perpendicular to the wafersurface, these pins are in the same plane as the wafer surface.

FIG. 12 is a top view of a chip probe wafer. The substrate 501 includesmultiple chip probes 500. Each of the chip probes 500 may bemanufactured using the process illustrated in FIG. 11.

FIG. 13 is a diagram of a checkerboard chip probe, which can be formedusing the technique for FIG. 11 or by other techniques, such as adamascene process with chemical mechanical planarization. The pattern inFIG. 13 is created by depositing metal layer, etching lines, overfilling, and repeating. One end can be etched to expose a portion of themetal rods. After matrix completion, conductor blocks are wire bonded atends. High current can be used to heat pins, which expand and compressthe insulator. Upon cooling, the wires shrink and separate from theinsulator. Note that the insulator squares may be slightly larger thanthe conductor squares, which means that the conductor squares may nottouch each other. A design such as that illustrated in FIG. 13 may beused on the bottom surface of, for example, the resistivity probe ofFIG. 1. In this example, the conductor squares extend further from thesurface than the insulator squares, which provides pins.

FIG. 14 is a cross-sectional block diagram of a probe head 600. Theprobe head 600 includes an insulator 601 and a cover 602. The cover 602completely encloses a cavity 603. Two inlets/outlets 603 areillustrated. These can provide and remove a fluid, such as clean, dryair.

Four needle bodies 604 are included. More or fewer needle bodies 604 canbe included. Each needle body 604 has a blunt needle tip. Each needlebody 604 also includes a shoulder 606, which can limit movement, and aconductive wire 607 in electronic communication with the needle 605. Theneedle bodies 604 can move within a hole in the insulator 601, such thatthe length which the needle bodies 604 extend from the insulator 601 canvary.

The fluid can be supplied with a controlled pressure and speed uniformlyacross all needle bodies 604. For example, the load acting upon theneedle bodies 604 can range from 0 kg/cm² to approximately 6 kg/cm².Unlike a conventional spring probe, the load may not decrease with aworn probe using the embodiment of FIG. 14. The fluid can either pushthe needle bodies 604 or can serve as a cushion or spring when theneedle bodies 604 are pushed into the cavity 603.

Using air pressure or pressure from another fluid can provide consistentforce per pin. Use of pressure from air or another fluid can compensatefor the tip surface changes (e.g., coned and rounded tips) as surfacearea increases and pressure per unit area decreases.

While illustrated with the pins 605, any of the pin embodimentsdisclosed herein can be used. In an instance where air pressure is usedthe enclosure may be sealed. In another instance a metal spring is usedand the enclosure is not sealed. In fixed pin designs the block holdingthe pins could be spring-loaded. In an embodiment, both pins and blockare fixed and the weight of the probe can determine the contactpressure.

FIG. 15 is block diagram of a probe head 600 on a control arm 703. Inthe system 700, the probe head 600 is positioned above a wafer 701 thatis disposed on a platen 702. The actuator 704 can move the control arm703 and, consequently, the probe head 600 toward and away from the wafer703. The probe head 600 also is in electronic communication with acontrol system 705 that can determine resistivity based on readings fromthe probe head 600.

During operation, a current may be passed between two pins on the probehead 600 and a voltage is measured between the other two pins on theprobe head 600. The pins of the probe head 600 may be arranged in asingle row or in multiple rows.

While the probe head of FIG. 14 is illustrated on the control arm 703,other probes can be used. For example, the probe 100 of FIG. 1 or theprobe of FIG. 18 can be used with the control arm 703.

FIG. 16 illustrates a bottom view of variable-shaped probe pins. FIG. 17illustrates a side view of the variable-shaped probe pins of FIG. 16.Variable shaped pins can provide closer pin spacing compared to roundpins that have a point in the center. In an instance, holes (includingtriangular holes) are etched and metal is deposited in the holes. Thisarrangement can be used to replace pins in any embodiment disclosedherein where all pins are identical shape.

FIG. 18 illustrates a second embodiment of a resistivity probe 800showing cross-sectional and corresponding top views. This resistivityprobe 800 can achieve long lifetime performance for multiple pin microprobes for measurement of sheet resistance, tunneling resistance inMRAM, or other film properties. The probes 802 are curved so that theelements are not parallel to a supporting surface (shown with dottedline 804) of the substrate 801 along their entire length. Dimensions ofthe elements and/or spacing may be sub-micron. The substrate 801 may besilicon and the probes 802 and layer 803 may be any metal or metal alloydisclosed herein. While four probes 802 are illustrated, more or fewermay be used. The resistivity probe 800 can improve on-contact areastability, reduce possibility of damaging test wafer surface, andprolong the lifetime of probe.

By having probes 802 extend out non-parallel to the supporting surfaceto form a curved cantilever, especially near the tip free end, thecontact angle is increased. This causes less contact area between asample surface and the probe 802 during landing at the same amount ofoverdrive toward a wafer surface.

In an instance, the angle of the probe 802 relative to the supportsurface can be made close to 90° (referring to the supporting body angleand total tip curved angle). By removing the non-conductive supportingcantilever material (e.g., the substrate 801), the contact area can bedetermined by the cross section of the cantilevered probe 802, which canbe formed by the conductive materials (or layered conductive materials).Thus, the contact area can be kept at a constant size, even during thewearing process, which improves measurement precision and the totallifetime of the probe.

Layered conductive materials can contain both soft and hard conductivematerials to achieve both good contact and ability to penetrate surfaceoxide layer. The probes 802 may not include non-conductive supportmaterials proximate the tips.

The substrate 801 (e.g., SiO₂) may be etched from the probes 802. Byremoving the substrate 801 (e.g., a support region) or anothersupporting non-conductive material, the stress is released so theconductive probe 802 can be curved yet conformal to each other. This canenable simultaneously landing onto a wafer surface.

FIGS. 19A-19E illustrate an embodiment of a manufacturing process forpart of the resistivity probe of FIG. 18. In FIG. 19A, a substrate 801(e.g., a glass plate) is molded. In FIG. 19B, a metal layer that formsthe probes 801 is deposited. In FIG. 19C, a metal layer 803 isdeposited. A mask also may be deposited. In FIG. 19D, the probes 801 areetched. In FIG. 19E, the support region of the substrate 801 is etched.

FIGS. 20A-20E illustrate another embodiment of a manufacturing processfor part of the resistivity probe of FIG. 18. In FIG. 20A, photoresist805 is deposited on the substrate 801 at a controlled angle. In FIG.20B, a metal layer that forms the probes 801 is deposited. In FIG. 20C,a metal layer 803 is deposited. A mask also may be deposited. In FIG.20D, the probes 801 are etched. In FIG. 20E, the support region of thesubstrate 801 and the photoresist 805 are etched and/or otherwiseremoved. While illustrated as angular, the photoresist 805 can bedeposited in a manner to provide a curve. Thus, the embodiment of FIGS.20A-20E can be used to form curved probes 801 as well as angular probes801.

In yet another embodiment, two layers of the material may be included inthe probes 802. Due to different stresses between the layers, the probes802 will curl when the substrate 801 is etched away from the probes 802.The other layer of material may be an insulator, such as SiO₂, siliconnitride, or silicon.

Although the present disclosure has been described with respect to oneor more particular embodiments, it will be understood that otherembodiments of the present disclosure may be made without departing fromthe scope of the present disclosure. Hence, the present disclosure isdeemed limited only by the appended claims and the reasonableinterpretation thereof.

What is claimed is:
 1. A resistivity probe comprising: a substratedefining a plurality of vias; a plurality of metal pins in one or morerows, wherein each of the metal pins is disposed in one of the vias, andwherein each of the metal pins extends out of the substrate; and aplurality of interconnects in the substrate, wherein the interconnectsprovide an electrical connection to the metal pins.
 2. The resistivityprobe of claim 1, wherein the metal pins are fabricated of tungsten,tungsten carbide, a tungsten-rhenium alloy, a beryllium-copper alloy, oran alloy containing gold, palladium, platinum, silver, copper, and zinc.3. The resistivity probe of claim 1, further comprising a plurality ofsprings, wherein each of the metal pins includes one of the springs. 4.The resistivity probe of claim 1, wherein the pins are in an arrayhaving at least two of the rows, and wherein each of the rows includesat least two of the metal pins.
 5. The resistivity probe of claim 1,further comprising: a plurality of needle bodies, wherein each of themetal pins is disposed on one of the needle bodies, wherein each of theneedle bodies includes a main body and a shoulder portion; a pluralityof conductive wires, wherein each of the conductive wires is disposed onone of the needle bodies; an enclosure, wherein each of the needlebodies is positioned to extend through a wall of the enclosure; and afluid source configured to direct a fluid into the enclosure, whereinthe needle bodies are configured to move through the enclosure uponexposure to the fluid, and wherein one of the shoulders is configured tohalt movement of the needle body that the shoulder is disposed on. 6.The resistivity probe of claim 5, further comprising an arm, wherein theenclosure is disposed on the arm.
 7. The resistivity probe of claim 6,further comprising a platen, wherein the arm is configured to move theenclosure toward and away from the platen.
 8. The resistivity probe ofclaim 1, further comprising an arm, wherein the substrate is disposed onthe arm.
 9. The resistivity probe of claim 8, further comprising aplaten, wherein the arm is configured to move the substrate toward andaway from the platen.
 10. A method comprising: etching a through hole ina base material of a substrate, wherein a wall of the through holedefines a cap stop; lining the wall of the through hole with a releaselayer; depositing metal in the through hole and cap stop; planarizingthe metal such that the metal is flush with the base material therebyforming a pin; and etching the release layer.
 11. The method of claim10, further comprising: lining the metal with the release layer afterthe planarizing; and depositing a conductor on the release layer priorto the etching, wherein the conductor and the metal are independent ofeach other after the etching.
 12. The method of claim 10, furthercomprising: depositing a conductor on the metal and the release layerafter the planarizing and prior to the etching, wherein the metal andthe conductor are in contact after the etching.
 13. The method of claim12, further comprising etching a tip of the metal at a point oppositethe conductor.
 14. The method of claim 10, wherein forming the pinfurther comprises depositing an insulator on the through hole and capstop prior to the lining.
 15. The method of claim 14, further comprisingetching a tip of the metal at a point opposite the conductor.
 16. Themethod of claim 14, further comprising grounding the base material. 17.The method of claim 14, further comprising depositing a ground layersurrounding the conductor.
 18. A resistivity probe comprising: asubstrate defining a top surface; and a plurality of probes extendingfrom the substrate, wherein each of the probes curves from the substrateto a tip of the probe such that each of the elements is non-parallel tothe top surface of the substrate.
 19. The resistivity probe of claim 18,wherein each of the probes includes two layers of material, wherein eachof the two layers have different stresses thereby causing the curve. 20.The resistivity probe of claim 18, wherein the substrate includes asupport region that matches a curve of the probes, and wherein thesupport region of the substrate is etched away.